This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A077630 #12 Sep 17 2021 17:29:43
%S A077630 0,6,18,18,86,54,344,162,650,486,3246,1458,11542,4374,19196,13122,
%T A077630 83672,39366,434242,118098,248278,354294,5669112,1062882,10522426,
%U A077630 3188646,5969216,9565938,46110338,28697814,271512140,86093442,149401156,258280326,583061114,774840978
%N A077630 Sum of terms in periodic part of continued fraction expansion of square root of 1+3^n.
%C A077630 a(1) = 0 since 3^1+1=4 is a square and sqrt(4) = 2 has no periodic part in its continued fraction expansion. - _Chai Wah Wu_, Sep 17 2021
%H A077630 Chai Wah Wu, <a href="/A077630/b077630.txt">Table of n, a(n) for n = 1..48</a>
%t A077630 Table[Apply[Plus, Last[ContinuedFraction[Sqrt[1+3^u]]]], {u, 1, 25}]
%Y A077630 Cf. A077624-A077635.
%K A077630 nonn
%O A077630 1,2
%A A077630 _Labos Elemer_, Nov 13 2002
%E A077630 a(1) corrected and a(26)-a(36) added by _Chai Wah Wu_, Sep 17 2021